oracle左外连接两个表答案

【问题标题】：oracle left outer join with two tablesoracle左外连接两个表
【发布时间】：2014-10-10 22:48:15
【问题描述】：

我有 3 张桌子，例如：

create table KOPA (MISS VARCHAR2(12), SER NUMBER(10));
create table NOTI (MISS VARCHAR2(12), LAI NUMBER(10), BAI NUMBER(10), ZAI NUMBER(10), KAI UMBER(10));
create table DOSI (MISS VARCHAR2(12), MAI NUMBER(10));

INSERT INTO KOPA (MISS,SER) VALUES ('AAA',123);
INSERT INTO KOPA (MISS,SER) VALUES ('BBB',234);
INSERT INTO KOPA (MISS,SER) VALUES ('CCC',345);
INSERT INTO KOPA (MISS,SER) VALUES ('DDD',456);
INSERT INTO KOPA (MISS,SER) VALUES ('EEE',567);
INSERT INTO KOPA (MISS,SER) VALUES ('TTT',456);
INSERT INTO KOPA (MISS,SER) VALUES ('YYY',567);
INSERT INTO KOPA (MISS,SER) VALUES ('III',456);

INSERT INTO NOTI (MISS,LAI,BAI,ZAI,KAI) VALUES ('AAA',1,2,3,NULL);
INSERT INTO NOTI (MISS,LAI,BAI,ZAI,KAI) VALUES ('BBB',1,2,3,NULL);
INSERT INTO NOTI (MISS,LAI,BAI,ZAI,KAI) VALUES ('CCC',1,2,3,NULL);
INSERT INTO NOTI (MISS,LAI,BAI,ZAI,KAI) VALUES ('FFF',1,2,3,NULL);
INSERT INTO NOTI (MISS,LAI,BAI,ZAI,KAI) VALUES ('GGG',1,2,3,NULL);
INSERT INTO NOTI (MISS,LAI,BAI,ZAI,KAI) VALUES ('HHH',1,2,3,NULL);
INSERT INTO NOTI (MISS,LAI,BAI,ZAI,KAI) VALUES ('III',1,2,3,NULL);
INSERT INTO NOTI (MISS,LAI,BAI,ZAI,KAI) VALUES ('JJJ',1,2,3,NULL);
INSERT INTO NOTI (MISS,LAI,BAI,ZAI,KAI) VALUES ('KKK',1,2,3,NULL);
INSERT INTO NOTI (MISS,LAI,BAI,ZAI,KAI) VALUES ('LLL',1,2,3,NULL);

INSERT INTO DOSI (MISS,MAI) VALUES ('BBB',4);
INSERT INTO DOSI (MISS,MAI) VALUES ('CCC',1);
INSERT INTO DOSI (MISS,MAI) VALUES ('DDD',2);
INSERT INTO DOSI (MISS,MAI) VALUES ('EEE',3);

SELECT * FROM KOPA A;
SELECT * FROM NOTI H;
SELECT * FROM DOSI B;

我要找的结果是：

a.miss a.ser h.lai h.bai h.zai b.miss b.mai
AAA    123   1     2     3     null   null
BBB    234   1     2     3     BBB    4
CCC    345   1     2     3     CCC    1
DDD    456   null  null  null  DDD    2
EEE    567   null  null  null  EEE    3
III    456   1     2     3     null   null

所以 - 问题是 - 我怎样才能用一张表获得两个外连接？像这样的：

select z.*,b.*
from (select a.miss,h.lai,h.bai from kopa a,noti h
where a.miss=h.miss and h.lai=1 and h.bai=2)z
full outer join dosi b on b.miss=z.miss

只是，有没有办法在每一行显示a.miss？

【问题讨论】：

标签： sql oracle select outer-join

【解决方案1】：

使用您的示例数据，此查询应该会为您提供所需的结果：

select a.miss, a.ser, h.lai, h.bai, h.zai, b.miss, b.mai
from kopa a
left join noti h on a.miss = h.miss and h.lai = 1 and h.bai = 2
left join dosi b on b.miss = a.miss
where h.miss is not null or b.miss is not null
order by a.miss

输出：

miss     ser         lai         bai         zai         miss         mai
-------- ----------- ----------- ----------- ----------- ------------ -----------
AAA      123         1           2           3           NULL         NULL
BBB      234         1           2           3           BBB          4
CCC      345         1           2           3           CCC          1
DDD      456         NULL        NULL        NULL        DDD          2
EEE      567         NULL        NULL        NULL        EEE          3
III      456         1           2           3           NULL         NULL

Sample SQL Fiddle

【讨论】：

【解决方案2】：

有没有办法在每一行显示a.miss？

要在每一行中显示 a.miss，请使用 LEFT JOIN

试试这个

select a.miss as a_miss, a.ser, h.lai, h.bai, h.zai, b.miss as b_miss, b.mai
from Kopa a
left outer join noti h on h.miss=a.miss
full outer join dosi b on b.miss=a.miss 
ORDER BY a.miss

SQL 小提琴：http://sqlfiddle.com/#!4/92e99/9

【讨论】：